Zinc catalyst/additive system for the polymerization of epoxide monomers

ABSTRACT

The present invention concerns a catalyst formulation comprising: (a) a Zn catalyst comprising a Zn compound having alcoholate ligand(s) derived from one or more polyols, and (b) a catalyst additive comprising a metal compound (i) having alcoholate ligand(s) derived from one or monohydric alcohol wherein the metal is selected from: (I) group 2 metals, preferably Mg, Ca, Sr, and Ba, more preferably Mg, (II) Li, and (III) combinations of at least two metals selected from (I) and (II). The present invention also relates to a process for polymerizing an epoxide monomer, preferably ethylene oxide, comprising carrying out the process in the presence of the catalyst formulation.

FIELD

The present invention relates to a new catalyst formulation comprising azinc alcoholate catalyst in combination with a metal alcoholateadditive. The catalyst formulation can be used to polymerize an epoxidemonomer, for example ethylene oxide.

BACKGROUND

Many catalysts are known for the ring opening polymerization of epoxidemonomers such as ethylene oxide. Examples of catalysts systems that areused for the industrial-scale production of poly(ethylene oxide) includecalcium-based and zinc-based types of catalysts.

Alkylene oxide polymerizations employing a zinc-based catalyst aredisclosed in the following references:

EP 0 239 973 A2 relates to zinc alkoxide and zinc aryloxide catalystsprepared from the reaction of a hydrocarbyl compound of zinc with adispersion of a polyol in an inert medium. It is taught that the use ofa dispersion aid such as fumed silica, magnesia or alumina and anonionic solvent are critical to achieving good dispersion of the polyolin the inert medium. In this way fine catalyst particles are created.Preferred are linear polyols having from 2 to 6 carbon atoms in thealkane chain (most preferred having 4 carbon atoms) or a cycloalkanediol having 5 or 6 ring carbon atoms. Dispersion prepared catalysts areuseful in the polymerization of cyclic alkylene oxides, e.g. ethyleneoxide and propylene oxide, to produce high molecular weight polymers andcopolymers.

U.S. Pat. No. 4,667,013 A describes as process for polymerizing alkyleneoxides in the presence of a catalyst dispersion similar to that in EP 0239 973 A2 above wherein a hydrogen-containing chain transfer agenthaving a pk_(a) value of from 9 to 22 is added to the polymerizingmixture to control the molecular weight of the resulting polymer. Thechain transfer agent is preferably an alkanol (aliphatic alcohol) havingfrom 1 to 16 carbon atoms.

U.S. Pat. No. 6,084,059 A details the preparation of metal alcoholatecatalysts (including zinc alcoholates) wherein an organometalliccompound is reacted with water or a active-hydrogen-containing compoundsuch as an aliphatic polyol using a micelle or reversed-micelletechnique facilitated by an ionic surfactant. The use of anionicsurfactants is said to be most effective at promoting formation ofmicelles or reversed micelles which are subsequently reacted with theorganometallic reagent such as diethylzinc to form an especially activecatalyst. It is taught that the use of dispersion promoters such asfumed silica is not essential.

U.S. Pat. No. 5,326,852 A concerns the production of alkylene oxidepolymers in the presence of a catalyst which is obtained by firstreacting a hydrocarbyl compound of zinc with an aliphatic polyhydricalcohol, then reacting the product with a monohydric alcohol having 1 to6 carbon atoms and finally applying a heat treatment at 80 to 200° C.

U.S. Pat. No. 6,979,722 B2 teaches the polymerization of an alkyleneoxide in the presence of a catalyst in a branched aliphatic hydrocarbonsolvent having 5 to 7 carbon atoms wherein the catalyst is a zinccompound obtained by the reaction of an organic zinc compound and analcohol. In the example the catalyst is prepared by first reactingdiethyl zinc with 1,4-butanediol and then with ethanol.

Catalyst systems for the alkylene oxide polymerization comprising Zn incombination with an additional metal are also known:

Polymer Letters, Vol 5, pp. 789-792 (1967) concerns bimetallicμ-oxo-alkoxides as catalysts for the polymerization of epoxides. Oneexemplary catalyst is Al₄Zn₂O₅(OC₄H₉)₆ which is used in thepolymerization of propylene oxide. There is no mention of zincalcoholates derived from polyols.

U.S. Pat. No. 3,607,785 A and DE 1 808 987 A describe the preparation ofa catalyst by first reacting an Al alkoxide with Zn acetate and thencontacting the resulting catalyst with a primary alcohol RCH₂OH. Thereis no mention of zinc alcoholates derived from polyols. In the examples,the catalyst is used to polymerize propylene oxide.

U.S. Pat. No. 3,459,685 A teaches the polymerization of alkylene oxideswith a catalyst system of a polymeric Al alcoholate and anorganometallic compound, for example methyl zinc phenoxide is mentioned.There is no mention of zinc alcoholates derived from polyols.

U.S. Pat. No. 3,542,750 A is directed to the polymerization of alkyleneoxides with a catalyst system of (a) the condensation product of Alhydroxide with an Al alcoholate and (b) an organometallic compound, forexample methyl zinc phenoxide. There is no mention of zinc alcoholatesderived from polyols.

DE 1 667 275 A and GB 1,197,986 A disclose a catalyst composition forthe polymerization of alkylene oxide which composition comprises thereaction product of a partially hydrolyzed A1 alkoxide and a group II orIII organometallic compound. The organometallic compound is preferablydiethyl zinc. There is no mention of zinc alcoholates derived frompolyols.

DE 1 937 728 A and relates to a process for polymerizing alkylene oxideby contacting it with a catalyst prepared by reacting (1) an Al alkoxidewith (2) phosphoric acid or an phosphoric acid monoester or diester, (3)an aliphatic alcohol and/or (4) a group II or III organometalliccompound such as for example diethyl zinc. There is no mention of zincalcoholates derived from polyols.

Zinc-based systems are also described as catalysts for the additionreaction of alkylene oxides with alkanols. U.S. Pat. No. 4,375,564 A isdirected to the preparation of low molecular weight alkanol alkoxylateshaving 1 to 30 alkylene oxide units. The catalyst system employed is acombination of a first component of a soluble basic compound of Mg and asecond component of a soluble basic compound of an element selected fromvarious metals including Zn. The preferred Mg compounds are Mgalkoxides, preferably having 1 to 30 carbon atoms. The preferred secondcomponent is a metal alkoxide, preferably having 1 to 30 carbon atoms,more preferably 1 to 6 carbon atoms, most preferred 2 or 3 carbon atoms.Alcoholates derived from polyols are not mentioned.

The problem addressed by the present invention is to provide a newcatalyst formulation that allows for the polymerization of epoxidemonomers such as ethylene oxide to access a greater range of productpolymer molecular weights including both higher and lower molecularweights than would be achievable with a zinc alkoxide catalyst alone.

SUMMARY

The problem is solved by a catalyst formulation comprising:

(a) a Zn catalyst comprising a Zn compound having alcoholate ligand(s)derived from one or more polyols, and

(b) a catalyst additive comprising a metal compound (i) havingalcoholate ligand(s) derived from one or monohydric alcohol wherein themetal is selected from:

-   -   (I) group 2 metals, preferably Mg, Ca, Sr, and Ba, more        preferably Mg,    -   (II) Li, and    -   (III) combinations of at least two metals selected from (I) and        (II).

The present invention also relates to the use of the above defined Zncatalyst in combination with the above defined catalyst additive in thepolymerization of an epoxide monomer, preferably ethylene oxide.

In another aspect the present invention is directed to a process forpolymerizing an epoxide monomer, preferably ethylene oxide, comprisingcarrying out the process in the presence of the above defined Zncatalyst and the above defined catalyst additive.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 and FIG. 2 illustrate the EO polymerizations described inExamples 6 and 5 in comparison to Comparative Example 4a and 4b,respectively.

DETAILED DESCRIPTION

The inventive catalyst formulation comprises (a) a Zn catalyst componentand (b) a catalyst additive component which comprises a metal compound(i) as defined above and optionally (ii) an alcohol and/or water.

The terms “Zn compound” and “metal compound” as used herein are notrestricted to a certain type of bonding between the metal and the“ligand(s)” and include coordination compounds, ionic compounds andcovalent compounds with no definitive distinction between each type ofbonding. In the same way, the terms “Zn alcoholate”, “Zn complex”,“metal alcoholate”, and “metal complex” are not restricted to compoundshaving a certain type of bonding between the metal and the “ligand(s)”and the bonds may have coordinative, ionic and/or covalent character.Accordingly, the term “ligand” is not restricted to true ligands in thenarrower sense that are bonded to a central metal atom or ion bycoordinative bonding to form a true complex compound, but the term“ligand” is herein used to describe the moiety that is bound to themetal by bonds that may have coordinative, ionic and/or covalentcharacter.

The Zn catalyst (a) comprises a Zn compound having alcoholate ligand(s)derived from one or more polyols (polyhydric alcohols). The Zn compoundis typically selected from:

(a1) a Zn alcoholate of one or more polyols, and

(a2) a heteroleptic Zn alcoholate of one ore more polyols and one ormore monohydric alcohols and/or water.

The polyol from which the alcoholate ligand(s) is/are derived istypically a diol although higher polyols such as triols, e.g. glycerine,may also be suitable. The polyol, preferably diol, is preferablyaliphatic or cycloaliphatic (preferably having 5 or 6 ring carbon atoms)or mixed aliphatic/cycloaliphatic comprising both aliphatic andcycloaliphatic moieties (preferably having 5 or 6 ring carbon atoms). Inother embodiments the polyol, preferably diol, is an aromatic polyolincluding mixed aliphatic/aromatic polyols comprising both aliphatic andaromatic moieties. The polyol, preferably diol, may comprise ahydrocarbon backbone with heteroatoms such as O and/or Si (e.g.polyether polyols such as polyalkylene polyols) in its backbone orheteroatoms such as O, Si and/or halogen, e.g. F, as part of functionalgroups (e.g. methoxy or trifluoromethyl groups) pendant from thebackbone. Typically, the Zn compound has alcoholate ligand(s) derivedfrom one or more alkanediols (which can be straight-chain or branched).In preferred embodiments the diol, preferably the alkanediol, has 2 to 8carbon atoms directly linking the oxygen atoms of the hydroxyl groups,more preferably 2 to 6 carbon atoms directly linking the oxygen atomsand most preferably 4 carbon atoms directly linking the oxygen atoms.Illustrative examples of suitable diols include ethylene glycol;diethylene glycol; triethyleneglycol; 1,2-propanediol; 1,3-propanediol;1,4-butanediol; 1,3-butanediol; 1,5-pentanediol; 1,6-hexanediol;1,2-cyclopentanediol (cis- and trans-); 1,2-cyclohexanediol (cis- andtrans-); 1,2-cyclohexanedimethanol (cis- and trans-);1,2-benzenedimethanol; (2,5-hexanediol (RR-, RS-, and SS-);2,5-dimethyl-2,5-hexanediol (RR-, RS-, and SS-); with 1,4-butanediolbeing especially preferred.

The polyol-derived alcoholate ligand(s) of the Zn compound constitutingthe Zn catalyst (a) (specifically including the Zn alcoholate (a1) andthe heteroleptic Zn alcoholate (a2)) can be derived from a single polyolor a mixture of at least two different polyols. Accordingly, the Znalcoholate (a1) can either be a homoleptic Zn alcoholate only comprisingone type of alcoholate ligand(s) or a heteroleptic Zn alcoholatecomprising at least two types of alcoholate ligands derived from atleast two different polyols, typically two different diols. In preferredembodiments the Zn compound (including the Zn alcoholate (a1) and theheteroleptic Zn alcoholate (a2)) has alcoholate ligand(s) that arederived from a single polyol, typically a single diol.

As regards the Zn alcoholate (a1), it is a homoleptic or heteroleptic Znalcoholate of any of the polyols as defined above including thepreferred embodiments. Typically, the Zn alcoholate (a1) is homoleptic.

In embodiment (a2), the heteroleptic Zn alcoholate comprises alcoholateligand(s) derived from one or more monohydric alcohols and/or water inaddition to alcoholate ligand(s) derived from polyol(s) as defined aboveincluding the preferred embodiments. In preferred embodiments, (a2) isheteroleptic Zn alcoholate of one ore more polyols and one or moremonohydric alcohols, i.e. the heteroleptic Zn alcoholate (a2) comprisesalcoholate ligand(s) derived from one or more polyols and alcoholateligand(s) derived from one or more monohydric alcohols. Typically, themonohydric alcohol is a monohydric aliphatic alcohol includingmonohydric halosubstituted aliphatic alcohols. Preferably, themonohydric alcohol is an alkanol (which can be straight-chain orbranched), more preferably a C₁ to C₁₀ alkanol, and most preferably a C₁to C₄ alkanol. Lower alkanols such as C₁ to C₄ alkanols are advantageousbecause they are volatile and can be easily removed from the Zn catalystduring preparation. Illustrative examples of suitable monohydric alcoholfrom which the alcoholate ligand(s) in the heteroleptic Zn alcoholate(a2) is/are derived include methanol; ethanol; 1-propanol; 2-propanol;1-butanol; 2-butanol; tert-butyl alcohol; iso-butyl alcohol; 1-pentanol;2-pentanol; 3-pentanol; 1-hexanol; 2-hexanol; 3-hexanol; 2-ethylhexanol; 1-heptanol; 2-heptanol; 3-heptanol; 4-heptanol;4-methyl-3-heptanol; 2,6-dimethyl-4-heptanol; 1-octanol; 2-octanol;3-octanol; 4-octanol; 1-methoxy-2-propanol; cyclohexanol;4-tert-butyl-cyclohexanol (cis- and trans-); 2,2,2-trifluoroethanol; and1,1,1-trifluoro-2-propanol, ethanol being especially preferred. Themonohydric alcoholate ligand(s) of the heteroleptic Zn alcoholate (a2)can be derived from a single monohydric alcohol or a mixture of at leasttwo different monohydric alcohols. If water is contained in theheteroleptic Zn alcoholate (a2) it is believed that it is incorporatedas a hydroxide, such as a terminal hydroxide or as an oxide which maybridge two zinc centers. Preferably, the monohydric alcoholate ligand(s)of the heteroleptic Zn alcoholate (a2) are derived from a singlemonohydric alcohol, more preferably from ethanol. In most preferredembodiments the Zn catalyst (a) is a heteroleptic Zn alcoholate (a2) of1,4-butanediol and a C₁ to C₄ alkanol such as ethanol.

The structures of Zn compounds (a1), (a2), and (a3) including thosepreferred Zn compounds mentioned above are often complex and difficultto resolve. This especially applies to the heteroleptic Zn complexes. Zncomplexes having alcoholate ligands are frequently dimeric, oligomericor even polymeric in structure with sometimes poorly defined structuresand may experience transformations between different structures.Bridging of two Zn atoms by one oxygen is known to occur. Thus, the Zncompounds (a1), (a2), and (a3) described herein explicitly includemonomeric, dimeric, oligomeric and polymeric species. As regardsheteroleptic Zn alcoholate (a2) (e.g. derived from one diol and onemonohydric alcohol or two different diols and one monol, or one diol andtwo different monohydric alcohols), it is possible that the product maycontain a combination of heteroleptic and homoleptic Zn alcoholates.

The Zn catalyst (a) of the present invention may comprise one single Zncompound having alcoholate ligand(s) derived from one or more polyols,preferably selected from those Zn compounds (a1) and (a2) as describedabove, or a mixture of at least two different Zn compounds, preferablyselected from those Zn compounds (a1) and (a2) as described above.

In some embodiments the Zn catalyst (a) comprises a Zn alcoholate (a1)of one or more polyols as described above and a Zn alcoholate (a3) ofone or more monohydric alcohols wherein the monohydric alcohols are asdefined above for the heteroleptic Zn alcoholate (a2). In theseembodiments the Zn alcoholate (a1) of one or more polyols and the Znalcoholate (a3) of one or more monohydric alcohols are often combinedwith a heteroleptic Zn alcoholate (a2) of one or more polyols and one ormore monohydric alcohols wherein the alcoholate ligand(s) are derivedfrom the same polyol(s) and monohydric alcohol(s) as in the Znalcoholate (a1) of one or more polyols and the Zn alcoholate (a3) of oneor more monohydric alcohols.

Preparation methods for the Zn compounds (a1), (a2), and (a3) have beendescribed previously, and a range of reagent stoichiometries, order ofaddition, and reaction temperature conditions are reported to producethese compounds.

The Zn alcoholates (a1) of the present invention are typically producedby reacting a dihydrocarbyl Zn compound with one or more polyols asspecified above. The dihydrocarbyl zinc compounds are preferably thealkyls and aryls of the general formula R₂Zn in which R is (1) an alkylgroup containing from 1 to 8 carbon atoms, preferably 1 to 6 carbonatoms, and most preferably 2 or 3 carbon atoms, or (1) phenyl ornaphthyl or alkyl-substituted phenyl or naphthyl groups in which thealkyl groups contain from 1 to 4 carbon atoms, preferably 1 to 3 carbonatoms, or (3) cycloalkyl groups containing from 4 to 6 ring carbonatoms; or (iv) the dicyclopentadienyl group. Illustrative thereof aredimethylzinc, diethylzinc, di-n-propylzinc, di-isopropylzinc,dibutylzinc (di-n-butylzinc, di-isobutylzinc, di-t-butylzinc),dipentlyzinc, dihexyl- and diheptyl- and dioctylzinc,di-2-ethylhexylzinc, diphenylzinc, ditolylzinc, dicyclobutylzinc,dicyclopentylzinc, di-methylcyclopentylzinc, dicyclohexylzinc, methylphenylzinc, methyl tolylzinc, methyl naphthylzinc, and ethyl phenylzinc.The nature of the zinc compounds is not critical but those possessingsome solubility in the reaction medium employed is advantageous. The useof a linear dialkylzinc as the starting material for the Zn alkoxidepreparation is preferred, diethyl zinc being most preferred. Exemplarypreparation routes to Zn alcoholates (a1) are taught in EP 0 239 973 A2,U.S. Pat. Nos. 5,326,852 A and 6,084,059 A.

The heteroleptic Zn alcoholates (a2) of the present invention aretypically prepared by reacting a dihydrocarbyl Zn compound as describedabove with one or more polyols as specified above and one or moremonohydric alcohols as specified above. Although it is preferred toreact first the dihydrocarbyl Zn compound with the polyol(s), followedby a reaction with the monohydric alcohol(s), the order of reaction maybe inverted or a mixture of all three components may be reactedsimultaneously. Regardless of how the components are reacted thereaction can be completed by a heat treatment step such as at 80 to 200°C. for 5 to 180 min which is typically carried out while distilling offthe unreacted alcohols. The equivalent ratio of polyol to dihydrocarbylZn compound is typically 0.2:1 to 1.1:1 and preferably 0.5:1 to 0.95:1.The equivalent ratio of monohydric alcohol to dihydrocarbyl Zn compoundis typically at least 0.1:1 and preferably 0.1:1 to 1.5:1. Fornon-volatile monohydric alcohols, stoichiometry should be carefullycontrolled to limit excess alcohol relative to zinc-C bonds. Acorresponding preparation method of heteroleptic Zn alcoholates (a2) istaught in more detail in U.S. Pat. Nos. 5,326,852 A. 6,979,722 B2describes in Example 1 the preparation of a heteroleptic Zn alcoholate(a2) from diethylzinc (1.0 molar equivalents), 1,4-butanediol (0.8 molarequivalents), and ethanol (1.3 molar equivalents) in hydrocarbonsolvent. The final catalyst is a white slurry.

The Zn alcoholates (a3) of one or more monohydric alcohols are typicallyproduced in a manner similar to that described for compounds (a2) with astoichiometry of 2.0 equivalents of monohydric alcohol to dialkylzincreagent. In the case that excess monohydric alcohol is used, volatilealcohols are preferred to facilitate removal of unreacted material.

The Zn compounds (a1), (a2) and (a3) may be obtained as an isolatedsolid powder (as for example described in EP 0 239 973 A2 and U.S. Pat.No. 5,326,852 A) or in the form of a slurry (as for example described inU.S. Pat. No. 6,979,722 B2) in solvent which slurry may be employeddirectly in the polymerization reaction.

Due to the air and moisture sensitivity of the Zn compounds (a1), (a2)and (a3) and their precursors conventional precautions are preferablytaken to exclude water and oxygen from the system (unless water is adesired reactant, see for example U.S. Pat. No. 6,084,059). This may beaccomplished by preparing and handling the Zn compounds in properlysealed apparatus together with an inert atmosphere such as nitrogen andoften includes drying of the reagents such as solvents to remove tracemoisture prior to preparation.

The catalyst additive component (b) comprises a metal compound (i)having alcoholate ligand(s) derived from one or monohydric alcohol andwherein the metal is selected from:

(I) group 2 metals such Mg, Ca, Sr, and Ba, preferably Mg,

(II) Li, and

(III) combinations of at least two metals selected from (I) and (II).

The monohydric alcohol from which the alcoholate ligand(s) of the metalcompound (i) is/are derived is typically aliphatic or cycloaliphatic(preferably having 5 or 6 ring carbon atoms) or mixedaliphatic/cycloaliphatic comprising both an aliphatic and cycloaliphaticmoieties (preferably having 5 or 6 ring carbon atoms). In otherembodiments the monohydric alcohol is an aromatic alcohol includingmixed aliphatic/aromatic alcohols comprising both aliphatic and aromaticmoieties. Within the meaning of the present application the term“alcohol” explicitly includes phenols. The monohydric alcohol maycomprise a hydrocarbon backbone with heteroatoms such as O and/or Si inits backbone or heteroatoms such as O, Si and/or halogen, e.g. F, aspart of functional groups (e.g. methoxy or trifluoromethyl groups)pendant from the backbone. Preferably, the monohydric alcohol is analiphatic alcohol, more preferably an alkanol (which can bestraight-chain or branched), and even more preferably an alkanolcomprising 1 to 20 carbon atoms, most preferably 3 to 12 carbons atoms.Illustrative examples of monohydric alcohols include ethanol, 1-propanol(n-propyl alcohol), 2-propanol (iso-propyl alcohol), 1-butanol (n-butylalcohol), 2-methyl-1-propanol (iso-butyl alcohol), 2-butanol (sec-butylalcohol), 2-metyhl-2-propanol (t-butyl alcohol), 2-ethylhexanol,octanol, nonanol, methoxypropanol, phenol, and methylphenols. Themonohydric alcoholate ligand(s) of the metal compound (i) can be derivedfrom a single monohydric alcohol or a mixture of at least two differentmonohydric alcohols. Preferably, the monohydric alcoholate ligand(s) ofthe metal compound (i) are derived from a single monohydric alcohol.

In some embodiments the metal compound (i) comprises only alcoholateligand(s), i.e. the metal compound (i) is a metal alcoholate (b1) of oneor more monohydric alcohols.

In other embodiments the metal compound (i) comprises non-alcoholateligand(s) in addition to the alcoholate ligand(s), i.e. the metalcompound (i) is a heteroleptic metal complex (b2) having alcoholateligand(s) derived from one or more monohydric alcohols andnon-alcoholate ligand(s). Examples of suitable non-alcoholate ligandsinclude ethylacetoacetate ligand(s), and 2,4-pentanedionate ligand(s).The heteroleptic metal complex (b2) can comprises one single type ofnon-alcoholate ligand or mixtures of at least two differentnon-alcoholate ligands. Typically, the heteroleptic metal complex (b2)comprises only one type of non-alcoholate ligand.

Preferred embodiments of the metal compound (i) comprise the preferredalcoholate and/or non-alcoholate ligand(s) in combination with thepreferred metals as described above.

Illustrative examples of metal compounds (b1) which may be used in thecatalyst additive (b) of the present catalyst formulation are magnesiumbis(2-ethylhexanolate) and lithium octanolate.

The structures of the metal compounds (b1) and (b2) including thosepreferred metal compounds (b1) and (b2) mentioned above are oftencomplex and difficult to resolve. This especially applies to theheteroleptic metal complexes. Metal complexes having alcoholate ligandsare frequently dimeric, oligomeric or even polymeric in structure withsometimes poorly defined structures and may experience transformationsbetween different structures. Bridging of two metal atoms by one oxygenis known to occur. Thus, the metal compounds (b1) and (b2) describedherein explicitly includes monomeric, dimeric, oligomeric and polymericspecies.

The catalyst additive (b) of the present invention may comprise a singlemetal compound (i) or a mixture of different metal compounds (i).

A lot of metal compounds (b1) and (b2) are commercially available.Others can be prepared by routes such as reaction of hydrocarbyl metalprecursors (such as di-n-butyl magnesium) with the appropriatestoichiometries of monohydric alcohol, or salt metathesis of the alkalisalt (e.g. Li) of the deprotonated monohydric alcohol with the precursormetal chloride of interest.

Due to the air and moisture sensitivity of the metal compounds (b1) and(b2) and their precursors conventional precautions are preferably takento exclude water and oxygen from the system. This may be accomplished bypreparing and handling the metal compounds (b1) and (b2) in properlysealed apparatus together with an inert atmosphere such as nitrogen andoften includes drying of the reagents such as solvents to remove tracemoisture prior to preparation.

In some embodiments the metal compounds (i), including metal compounds(b1) and (b2) are soluble in a hydrocarbon solvent. Their preparationmay result in a solution of the metal compound (i) in a hydrocarbonsolvent which solution may be employed directly in the polymerizationreaction.

The catalyst additive (b) may further contain an alcohol (ii) as anoptional component. The term “alcohol” is used herein in contrast to theterm “alcoholate” and designates an alcohol which is not deprotonated.Typically the alcohol (ii) is an aliphatic, cycloaliphatic or aromaticalcohol. It is preferred that the alcohol is monohydric. The alcohol,more specifically the monohydric alcohol, is preferably an aliphatic,cycloaliphatic (preferably having 5 or 6 ring carbon atoms) or mixedaliphatic/cycloaliphatic alcohol comprising both an aliphatic andcycloaliphatic moiety (preferably having 5 or 6 ring carbon atoms); anaromatic alcohol or a mixed aliphatic/aromatic alcohol comprising bothaliphatic and aromatic moieties. More preferably, the alcohol, typicallythe monohydric alcohol, is an alkanol (which can be straight-chain orbranched) and even more preferably, an alkanol comprising 1 to 20 carbonatoms, and most preferably 4 to 12 carbons atoms. Illustrative examplesof alkanols include methanol, ethanol, 1-propanol (n-propyl alcohol,2-propanol (iso-propyl alcohol), 1-butanol (n-butyl alcohol), 2-butanol(sec-butyl alcohol), 2-methyl-1-propanol (iso-butyl alcohol),2-methyl-2-propanol (tert-butyl alcohol, 2-ethylhexanol, and octanol.

The catalyst additive (b) may comprise a single alcohol (ii) or amixture of different alcohols (ii). The alcohol (ii) that is used in thecatalyst composition (b) in addition to the metal compound (i) may bethe same as the alcohol from which the alcoholate ligand(s) in metalcompound (i) is/are derived. However, it is not mandatory that thealcohol (ii) corresponds to the alcoholate ligand(s) of metal compound(i).

It is not essential for the present invention whether and how thealcohol (ii) is bound to the metal compound (i)/the metal of the metalcompound (i). In some cases the alcohol (ii) forms an adduct with themetal compound (i). A variety of alcohol adducts of metal alcoholates(b1) is commercially available. In other embodiments the alcohol (ii) isadded to the metal compound (i) to become a component of the catalystadditive (b). The alcohol (ii) may also be formed in situ by addingwater to the metal compound (i) to react with part of the alcoholateligand(s) of the metal compound (i), typically metal alcoholate (b1).

The Zn alkoxide catalyst (a) can be used together with the catalystadditive (b) in a conventional process for polymerizing an epoxide,typically in a suspension polymerization process. The novel catalystformulation of this invention is useful in effecting the polymerizationof epoxide monomers which contain a cyclic group composed of two carbonatoms and one oxygen atom. Typically, these epoxide monomers can becharacterized by the following formula:

wherein each R¹, individually, can be hydrogen, haloaryl, or ahydrocarbon radical free from ethylenic and acetylenic unsaturation suchas, for example, alkyl, aryl, cycloalkyl, aralkyl, or alkaryl radicals.In addition, both R¹ variables together with the epoxy carbon atoms,i.e. the carbon atoms of the epoxy group can represent a saturatedcycloaliphatic hydrocarbon nucleus which contains from 4 to 10 carbonatoms, preferably from 4 to 8 carbon atoms, for example, a saturatedcycloaliphatic hydrocarbon nucleus derived from cycloalkane, alkylsubstituted cycloalkane, cyclobutane, cyclopentane, cyclohexane,cycloheptane, cyclooctane, methylcyclopentane, or amylcyclohexane.Illustrative R¹ radicals include, among others, methyl, ethyl, propyl,butyl, isobutyl, hexyl, isohexyl, 3-propylheptyl, dodecyl, octadecyl,phenyl, halophenyl, chlorophenyl, bromophenyl, benzyl, tolyl,ethylphenyl, butylphenyl, phenethyl, phenylpropyl, cyclopentyl,cyclohexyl, 2-methylcyclohexyl, and cycloheptyl.

A single epoxide monomer or an admixture of at least two differentepoxide monomers can be employed as the monomeric feed. A broad range ofepoxide monomers can be used in the polymerization process andrepresentative expoxide monomers include, for example, ethylene oxide,propylene oxide, 1,2-butylene oxide, 2,3-butylene oxide, theepoxypentanes, the epoxyhexanes, 2,3-epoxyheptane, nonene oxide,5-butyl-3,4-epoxyoctane, 1,2-epoxydodecane, 1,2-epoxyhexadecane,1,2-epoxyoctadecane, 5-benzyl-2,3-epoxyheptane,4-cyclo-hexyl-2,3-epoxypentane, chlorostyrene oxide, styrene oxide,ortho-, meta-, and para-ethylstyrene oxide, glycidyl benzene, theoxabicycloalkanes and alkyl-substituted oxabicycloalkanes, e.g.,7-oxabicyclo[4.1.0]heptane, oxabicyclo[3.1.0]hexane,4-propyl-7-oxabicyclo[4.1.0]heptane, and3-amyl-6-oxabicyclo[3.1.0]hexane.]

It is preferred that the epoxide monomer is an olefin oxide, morepreferably an olefin oxide having 2 to 20 carbon atoms, such as forexample ethylene oxide, propylene oxide, 1,2-epoxy-butane, or2,3-epoxybutane. The most preferred monomer is ethylene oxide.Outstanding results are achieved in polymerizing ethylene oxide via thatsuspension polymerization route.

“Polymerization of an olefin oxide, preferably ethylene oxide” as usedherein typically does not encompass the preparation of oligomers, suchas polyethylene glycols and their mono- and diethers having a weightaverage molecular weight of less than 30,000, as determined by sizeexclusion chromatography. Accordingly, the term “polymerization of anolefin oxide, preferably ethylene oxide” typically means the preparationof a poly(olefin oxide), preferably poly(ethylene oxide), having aweight average molecular weight of at least 30,000, more preferably atleast 50,000, and most preferably at least 80,000, as determined by sizeexclusion chromatography.

It is further understood that the catalytically active species thatfacilitate the polymerization of the epoxide monomer may be structurallydifferent from the Zn compound of the Zn catalyst (a) and the metalcompound (i) as they are present in the inventive catalyst formulationprior to addition to the starting materials of the polymerizationreaction. In the reaction system the Zn compound of the Zn catalyst (a)and/or the metal compound (i) may react with other components which arepresent intentionally (e.g. the optional protonated alcohol (ii)) orunintentionally such as trace amounts of water (to form partiallyhydrolyzed alkoxides/alcoholates) to result in the catalytically activespecies.

The sequence of adding the Zn catalyst (a), the metal compound (i) andthe optional alcohol (ii) to the reaction system is not essential. TheZn catalyst (a), the metal compound (i) and the optional alcohol (ii)may be premixed prior to addition to the reaction system to form acatalyst formulation or they may be added separately, eithersubsequently or at least two of them simultaneously. Continuous orsemi-continuous addition of one or two or all of the Zn catalyst (a),the metal compound (i) and the optional alcohol (ii) is also possible.

The form in which the Zn catalyst (a) and the metal compound (i) areadded to the reaction system is also not crucial. Typically, the Zncatalyst (a) is introduced in the form of a solution or suspension whichmay be obtained either directly from the preparation of the catalyst orby dissolving or dispersing the solid Zn catalyst (a) in an appropriatesolvent. Suitable solvents include aliphatic hydrocarbons such asisopentane, hexane, octane, decane or dodecane. Typically, the metalcompound (i) is introduced in the form of a solution or suspension whichmay be obtained either directly from the preparation of the catalyst orby dissolving or dispersing the solid metal compound (i) in anappropriate solvent. Again, suitable solvents include aliphatichydrocarbons such as isopentane, hexane, octane, decane or dodecane.

In typical embodiments, the Zn catalyst (a) (including Zn compounds(a1), (a2), and (a3) and preferred embodiments mentioned before) is usedin the polymerization of an epoxide monomer, such as ethylene oxide, inan amount providing 1 mol of Zn per 10 to 100,000 mol of epoxidemonomer, preferably 1 mol of Zn per 10 to 50,000 mol of epoxide monomer,more preferably 1 mol of Zn per 100 to 20,000 mol of epoxide monomer,even more preferably 1 mol of Zn per 200 to 10,000 mol of epoxidemonomer, and most preferably 1 mol of Zn per 250 to 5,000 mol of epoxidemonomer or 1 mol of Zn per 250 to 2,500 mol of epoxide monomer.

The metal compound (i) (including metal compounds (b1) and (b2) andpreferred embodiments mentioned before) is preferably used in an amountproviding a molar ratio of metal of the metal compound (i) to Zn of theZn catalyst (a) (including Zn compound (a1), (a2), and (a3) andpreferred embodiments mentioned before) within the range of from 0.01:1to 20:1, more preferably from 0.05:1 to 15:1, even more preferably from0.05:1 to 10:1, most preferably from 0.05:1 to 8:1 or from 0.1:1 to 8:1.

When an alcohol (ii) is used together with the metal compound (i) ascatalyst additive (b) the alcohol is preferably used in an amountproviding a molar ratio of alcohol (ii) to metal of the metal compound(i) within the range of from 0.01:1 to 5:1, more preferably from 0.05:1to 2:1, and most preferably from 0.1:1 to 0.5:1.

Accordingly, preferred embodiments of the catalyst formulation comprisethe Zn catalyst (a) and the catalyst additive (b) in relative amountsrealizing the above ratios, i.e., the Zn catalyst (a) and the metalcompound (i) in amounts to provide a molar ratio of metal of the metalcompound (i) to Zn of the Zn catalyst (a) within the range of from0.01:1 to 20:1, more preferably from 0.05:1 to 15:1, even morepreferably from 0.05:1 to 10:1, most preferably from 0.05:1 to 8:1 orfrom 0.1:1 to 8:1, and alcohol (ii) in an amount providing a molar ratioof alcohol (ii) to metal of the metal compound (i) within the range offrom 0 to 5:1, preferably 0.01:1 to 5:1, more preferably from 0.05:1 to2:1, and most preferably from 0.1:1 to 1:1.

The polymerization reaction can be conducted over a wide temperaturerange. Polymerization temperatures can be in the range of from −50 to150° C. and depend on various factors, such as the nature of the epoxidemonomer(s) employed, the particular catalyst employed, and theconcentration of the catalyst. A typical temperature range is from 0 to150° C. For the preparation of granular poly(ethylene oxide) a reactiontemperature below 70° C. is preferred. Though granular poly(ethyleneoxide) can be prepared at a reaction temperature of about 65 to 70° C.the poly(ethylene oxide) product tends to accumulate on the interiorsurfaces of the reaction equipment. Consequently, it is preferred thatthe reaction temperature for the preparation of granular poly(ethyleneoxide) be in the range of from −30 to 65° C. and more preferably from 0to 60° C.

The pressure conditions are not specifically restricted and can beadjusted by the temperature of the polymerization reaction, the vaporpressures of the inert diluents and monomer(s), and the pressure ofinerting gas (e.g. nitrogen) introduced into the reactor.

In general, the reaction time will vary depending on the operativetemperature, the nature of the epoxide oxide reagent(s) employed, theparticular catalyst combination and the concentration employed, the useof an inert diluent, and other factors. Polymerization times can be runfrom minutes to days depending on the conditions used. Preferred timesare 1 to 10 h.

When polymerizing an admixture containing two different epoxidemonomers, the proportions of said epoxides can vary over the entirerange.

The polymerization reaction preferably takes place in the liquid phase.Typically, the polymerization reaction is conducted under an inertatmosphere, e.g. nitrogen. It is also highly desirable to effect thepolymerization process under substantially anhydrous conditions.Impurities such as water, aldehyde, carbon dioxide, and oxygen which maybe present in the epoxide feed and/or reaction equipment should beavoided. The polymers of this invention can be prepared via the bulkpolymerization, suspension polymerization, or the solutionpolymerization route, suspension polymerization being preferred.

The polymerization reaction can be carried out in the presence of aninert organic diluent such as, for example, aromatic hydrocarbons,benzene, toluene, xylene, ethylbenzene, and chlorobenzene; variousoxygenated organic compounds such as anisole, the dimethyl and diethylethers of ethylene glycol, of propylene glycol, and of diethyleneglycol; normally-liquid saturated hydrocarbons including the open chain,cyclic, and alkyl-substituted cyclic saturated hydrocarbons such aspentane (e.g. isopentane), hexane, heptane, octane, variousnormally-liquid petroleum hydrocarbon fractions, cyclohexane, thealkylcyclohexanes, and decahydronaphthalene.

Typical initial concentrations of ethylene oxide in the solvent rangefrom 0.3 to 3 M, preferably from 0.3 to 2.5 M, more preferably from 0.4to 2 M, and most preferably from 0.5 to 1.5 M (not considering thevapor-liquid equilibrium of ethylene oxide in the system). As thoseskilled in the art recognize, ethylene oxide polymerizations areextremely exothermic, and practitioners must consider heat removal (ortemperature control) in the determination of run conditions. Initialconcentrations may be achieved by an ethylene oxide precharge, addedbefore the catalyst addition, or by an ethylene oxide charge followingthe catalyst introduction to the diluent.

The suspension polymerization can be conducted as a batch,semi-continuous, or a continuous process.

The single components of the polymerization reaction, i.e. the epoxidemonomer, the Zn catalyst (a), the metal compound (i), the optionalalcohol (ii) and the diluent, if used, may be added to thepolymerization system in any practicable sequence as the order ofintroduction is not crucial for the present invention. However, shouldthe Zn catalyst (a) and monomer be introduced prior to the addition ofcatalyst additive component (b), it is possible that some fraction ofthe product will not be influenced by the effect of catalyst additive(b). It may also be undesirable to add catalyst or additive to thereactor prior to the diluents, as these reagents may be difficult todisperse once they have contacted the reactor walls.

The present invention provides for new options in the polymerization ofepoxide monomers such as ethylene oxide. It is quite surprising that theuse of metal compounds (i) which themselves are not competentpolymerization catalysts under standard reaction conditions incombination with a Zn catalyst (a) influences the polymerizationmechanism. It is further unexpected that in some cases the presence ofan additional alcohol (ii) in combination with the metal compounds (i)is not detrimental to the catalyst system as alcohol alone can be apotent catalyst poison, drastically dropping catalyst productivity. Insome cases the inventive catalyst additives (b) may increase catalystreactivity in terms of rate and/or productivity and/or allow for thesynthesis of new polymer products. When compared to control reactionsonly comprising the Zn catalyst (a) but not containing the catalystadditive (b), in some embodiments the additive-containing polymerizationreactions according to the present invention demonstrate enhancedreaction rate and productivity, and in certain embodiments they produceexceptionally high molecular weight materials, as determined by theviscosity of aqueous solutions. In other embodiments, when compared tocontrol reactions not containing catalyst additive (b), theadditive-containing reactions according to the present inventiondemonstrate comparable reaction rate and productivity, while producinglower molecular weight materials, as determined by the viscosity ofaqueous solutions.

As the reaction mechanism is not completely understood it is difficultto predict the effect a specific claimed Zn catalyst/additivecombination. Different additives effect the polymerization differently.Not only the nature of the catalyst additive (b) but also the specificratio in which the single components of the catalyst system are used maycontrol whether the additive acts as a rate and molecular weightenhancer or a molecular weight reducing (or limiting) agent. However,only a limited number of experiments are necessary to allow the personskilled in the art to identify some general trends in the system underconsideration.

In some cases the catalyst additives (b) have the effect of enhancingthe reactivity of the Zn catalyst (a) in terms of rate and/orproductivity. Certain catalyst additives (b) have the effect ofsignificantly increasing the molecular weight of the polymer productrelative to catalyst runs without additives. Typically, with these typesof catalyst additives polymer, especially poly(ethylene oxide), havingmolecular weights above 8,000,000 based on viscosity determination maybe obtained. An increase of catalyst reactivity is typically achievedwith embodiments wherein the catalyst additive (b) only comprises themetal alcoholate (i) but no additional alcohol (ii), i.e. no freealcohol has been added to the polymerization reaction. An exemplaryclass of catalyst additives (b) that act as reactivity and molecularweight enhancers are the alcoholates of Mg that are soluble in C₅-C₁₄hydrocarbon solvents such as the magnesium alkoxide of 2-ethyl hexanol[Mg(OC₈H₁₇)₂]. For some catalyst additives (b) such as for lithiumoctanolate little molecular weight enhancement is observed, but theystill act as reactivity enhancers. Those exemplary additives (b) areused in combination with the Zn catalyst (a) as described aboveincluding the preferred embodiments.

In other cases the use of catalyst additives (b) in addition to the Zncatalyst (a) allows to directly synthesize lower molecular weightpolymers while sometimes maintaining catalyst activity as measured bypolymerization rate and catalyst productivity. In these cases theadditive (b) acts as molecular weight reducing (or limiting) agent,i.e., some of the catalyst additives (b) are useful to facilitate theproduction of lower molecular weight polymers, especially lowermolecular weight poly(ethylene oxide), if used in combination with theZn catalyst (a). Typically with these types of catalyst additives,polymers, especially poly(ethylene oxide), having molecular weights of100,000 to 2,000,000 based on viscosity determination may be obtained.The direct synthesis of lower molecular weight poly(ethylene oxide) is asignificant progress in current ethylene oxide polymerization technologyas techniques to control the molecular weight of poly(ethylene oxide)are lacking. Typically, reactor grades of poly(ethylene oxide) range inmolecular weight from 4,000,000 to >8,000,000 based on viscositydetermination. The polymer obtained must be irradiated to produce lowermolecular weight grades (100,000 to 2,000,000). This additional processadds cost and effects long product cycle times. Embodiments wherein theZn catalyst (a) is combined with a catalyst additive (b) comprising anadditional alcohol (ii) as defined above in addition to the metalalcoholate (ii) typically act as molecular weight reducing agents, i.e.allow synthesis of polymer having lower molecular weight than obtainedwith the Zn catalyst (a) alone in absence of the additive. However, thepresence of the alcohol (ii) is not mandatory to effect a reduction inmolecular weight since this effect can also be observed in absence of analcohol (ii). Exemplary catalyst additives (b) that act as molecularweight control agents are Mg alkoxides that are soluble in C₅-C₁₄hydrocarbon solvents in combination with an alcohol (ii) such as themagnesium alkoxide of 2-ethyl hexanol [Mg(OC₈H₁₇)₂] plus 2-ethylhexanol. Those exemplary additives (b) are used in combination with theZn catalyst (a) as described above including the preferred embodiments.

The above term “molecular weight based on viscosity determination”refers to an approximate molecular weight (rough molecular weightestimation) that is assigned to the polymer on the basis of its solutionviscosity according to Table 1.

TABLE 1 Approximate Weight Fraction Brookfield Spindle Time fromviscometer Molecular of Polymer in Viscometer speed motor start toreading Viscosity range Weight Aqueous Solution Spindle No. (rpm) (min)(mPa · s or cP) >8,000,000 1% 2 2 5 >15,000 8,000,000 1% 2 2 510,000-15,000 7,000,000 1% 2 2 5  7,500-10,000 5,000,000 1% 2 2 55,500-7,500 4,000,000 1% 2 2 5 1,650-5,500 2,000,000 2% 3 10 12,000-4,000 1,000,000 2% 1 10 1 400-800 900,000 5% 2 2 5  8,800-17,600600,000 5% 2 2 5 4,500-8,800 400,000 5% 1 2 5 2,250-4,500 300,000 5% 210 1  600-1,200 200,000 5% 1 50 0.5  65-115 100,000 5% 1 50 0.5 12-50

Viscosity values which do not exactly fit with the ranges specified inthe last column but lie between those ranges correspond to intermediatevalues of molecular weight.

The viscosity is measured on water/isopropyl alcohol solutions ofpolymer at 25.0° C. using a Brookfield rotational viscometer with theviscometer settings for each molecular weight as indicated in Table 1.The term “1% aqueous solution viscosity” as used in the table means thedynamic viscosity of a 1 weight % solution of the polymer in a mixtureof water and isopropyl alcohol. The same definition applies to 2 and 5%solutions. The weight percentage of polymer is based on the weight ofwater only, i.e. not including the isopropyl alcohol. Preparing theaqueous solutions of the polymers the isopropyl alcohol is added firstin order to allow the polymer particles to disperse as individualsbefore water is added. This seems to greatly minimize gel formation andprovides reliable viscosity measurements. The detailed procedure fordissolving the polymers is found in Bulletin Form No. 326-00002-0303AMS, published March 2003 by the Dow Chemical Company and entitled“POLYOX™ Water-Soluble Resins Dissolving Techniques”. The solution isprepared from material which passes through a 20 mesh screen in a clean,dry 800 mL low form beaker. (Virtually all of the product passes throughthe 20 mesh screen.) The appropriate amount of material is weighed intothe beaker: 6.000 g for a 1 wt. % solution; 12.000 g for a 2 wt. %solution; or 30.000 g for a 5 wt. % solution. In a second beaker therequired amount of high purity water is weighed (594 g for a 1 wt. %solution; 588 g for a 2 wt. % solution and 570 g for a 5 wt. %solution). To the polymer containing beaker is then added 125 mL ofanhydrous isopropanol and the resulting mixture is slurried with amechanical agitator (the agitator and additional experimental detailsare described more specifically in the above mentioned Dow bulletin).The stirrer is adjusted to move the bottom propeller as close to thebottom of the beaker as possible, and the mixture is stirred at 300-400rpm in order to form a well distributed slurry. To this slurry is thenadded the appropriate premeasured amount of water in a continuousstream. The mixture is then stirred at 300-400 rpm for approximately 1minute and then at 60 rpm for 3 hours. An appropriate beaker covershould be used to prevent evaporation during solution preparation. Afterthe agitation procedure the solution is inspected for gels. If thesolution contains significant gels it must be remade, as the viscositymeasurement will be inaccurate. A person skilled in the art willrecognize this phenomenon and understand its impact on rheologicalevaluation. If the solution is acceptable, it is incubated for 1 hour at25.0° C. prior to the Brookfield viscosity measurement.

In preparation for the measurement the appropriate viscometer spindle isimmersed in the polymer solution, avoiding entrapping air bubbles, andattached to the viscometer shaft. The height is adjusted to allow thesolution level to meet the notch on the spindle. The viscometer motor isactivated, and the viscosity reading is taken at a specified timeinterval following the start of the viscometer motor.

Some embodiments of the invention will now be described in detail in thefollowing examples.

EXAMPLES

Solvents used in the examples (Isopar™E, hexanes, n-hexane, decane) werepurified over activated A2 alumina to remove residual moisture. Isopar™Eand hexanes were also purified over activated Q5 catalyst to removeresidual oxygen.

The viscosities of the polymers referred to in the examples weremeasured on water/isopropyl alcohol solutions of polymer at 25.0° C.using a Brookfield rotational viscometer with the viscometer settings asindicated in Table 1. The corresponding solutions were prepared asdescribed above.

Reference Example 1 Preparation of Zinc Alkoxide Catalyst in Isopar™(Heteroleptic Zn Alcoholate of 1,4-Butanediol and Ethanol)

A zinc alkoxide catalyst was prepared guided by the description providedin U.S. Pat. No. 6,979,722 B2, Example 1. A 250 mL flask was set up inan inert atmosphere glovebox and charged with Isopar™ E (isoparaffinicfluid, CAS 64741-66-8) (80 mL) and diethyl zinc (5.0 mL, 48.8 mmol). Tothis solution, 1,4-butanediol (3.5 mL, 39.5 mmol, dried over molecularsieves) was added dropwise with vigorous stirring. A white precipitateformed immediately. The solution was stirred at room temperature for 1h, heated to 50° C. for 1 h, and then stirred overnight at roomtemperature. The following day anhydrous ethanol (3.7 mL, 63.4 mmol) wasdripped into the solution. The solution was then heated to 40° C. for 1h, followed by heating to 150° C. for 1 h. At this temperature, volatilecomponents from the solution (including some of the Isopar™ E) weredistilled off. After cooling, the final slurry volume was adjusted to120 mL with Isopar™ E, to give a Zn concentration of 0.4 M. Thiscatalyst preparation was used in the described polymerization reactions,and is subsequently described as “zinc alkoxide catalyst.” The catalystwas always kept in an inert atmosphere glove box, and solutions for usein the polymerization reactions were also prepared in the glovebox.Catalyst solutions were sealed in serum-type vials for transport to thereactor and were delivered to the reaction solution by syringing out ofthe sealed vials and injecting into the sealed reactor in order tominimize air exposure.

Reference Example 2 Preparation of Magnesium Alkoxide Additive

Magnesium-bis-(2-ethylhexanolate) was prepared in an inert atmosphereglovebox in hexanes from 15.0 mL of a 1.28 M hexanes solution of2-ethylhexanol (19.2 mmol) and 9.6 mL of 1M di-n-butylmagnesium inheptane (9.6 mmol).

Reference Example 3 Preparation of Lithium Alkoxide Additive

Lithium octanolate was prepared under inert atmosphere by the additionof 2M n-butyllithium in cyclohexane (4.8 mL, 9.6 mmol) to a hexanesolution (50 mL) of anhydrous octanol (1.550 mL, 9.80 mmol).

Comparative Example 4a Polymerization of Ethylene Oxide with Zn AlkoxideCatalyst

A glass 2 L reactor equipped with a condenser system, ethylene oxide(EO), feed line, over head stirrer, and septum sealed port for catalystaddition, was dried overnight under a nitrogen flow at elevatedtemperature. After cooling, the inerted reactor was charged with 700 mLof isopentane and 1.5 g of CAB-O-SIL® TS-720 hydrophobically modifiedsilica (commercially available from Cabot Corporation) and equilibratedto 38° C. and 89.6 kPa (13 psi). An ethylene oxide precharge of 34 g wasadded to the reactor, followed by injection through the septum port of 6mL of the 0.4 M zinc alkoxide catalyst slurry prepared in ReferenceExample 1. Ethylene oxide was continuously fed into the reactor until100 g total had been added. The rate of ethylene oxide addition wasadjusted so that the calculated solution concentration of ethylene oxidewould stay below 7 wt. %. After 285 min, 1.5 mL of isopropyl alcoholwere charged into the reactor and the reactor was cooled. The solidpolymer product was isolated by filtration, dried in a vacuum oven overnight at room temperature, and stabilized with 500 ppmbutylhydroxytoluene (BHT). The poly(ethylene oxide) (PEO) yield was 73.3g. A 1 wt. % aqueous solution of the polymer product was determined tohave a viscosity of 3,400 mPa·s (spindle no. 2, 2 rpm, 5 min measurementtime).

Comparative Example 4b Polymerization of EO with Zinc Alkoxide Catalyst

EO polymerization was carried out as described in Comparative Example4a. Here the catalyst solution was injected into a reactor prechargedwith 30 g of ethylene oxide. After 268 min, the EO solutionconcentration was 2.6 wt. %, 1.5 mL of isopropyl alcohol were chargedinto the reactor at this time and the reactor was cooled. The polymerwas isolated and stabilized as described in Comparative Example 4a. ThePEO yield was 80.8 g. A 1 wt. % aqueous solution of the polymer productwas determined to have a viscosity of 4860 mPa·s (spindle no. 2, 2 rpm,5 min measurement time).

Example 5 Polymerization of EO with Zinc Alkoxide Catalyst and MagnesiumAlkoxide Additive

EO polymerization was carried out as described in Comparative Example4a. Here, the catalyst was pre-mixed with an additive solution beforebeing added to the EO charged reactor. After the di-n-butylmagnesium and2-ethylhexanol reagents reacted to formmagnesium-bis-(2-ethylhexanolate) as described in Reference Example 2, 6mL of 0.4 M zinc alkoxide catalyst slurry of Reference Example 1 wereadded to the solution. The resulting mixture was sealed in a serum vialfor transport to the reactor, and the catalyst/additive solution wasinjected into a reactor precharged with 40 g of EO. After 100 min, theEO solution concentration was 0.1 wt. %, 1.5 mL of isopropyl alcoholwere charged into the reactor at this time and the reactor was cooled.The polymer was isolated and stabilized as described in ComparativeExample 4a. The PEO yield was 94.9 g. A 1 wt. % aqueous solution of thepolymer product was determined to have a viscosity of 17,900 mPa·s(spindle no. 2, 2 rpm, 5 min measurement time).

Example 6 Polymerization of EO with Zinc Alkoxide Catalyst and LithiumAlkoxide Additive

2-3 hours prior to the polymerization reaction 6 mL of zinc alkoxidecatalyst slurry of Reference Example 1 were injected into a solution oflithium octanolate of Reference Example 3. EO polymerization was carriedout as described in Comparative Example 4a except that the zinc alkoxidecatalyst plus lithium additive solution was used instead of zincalkoxide catalyst alone. The EO precharge was 36 g. After 117 min, 1.5mL of isopropyl alcohol were charged into the reactor and the reactorwas cooled. The polymer was isolated and stabilized as described inComparative Example 4a. The PEO yield was 99.0 g. A 1 wt. % aqueoussolution of the polymer product was determined to have a viscosity of3,360 mPa·s (spindle no. 2, 2 rpm, 5 min measurement time).

FIG. 1 and FIG. 2 illustrate the EO polymerizations described inExamples 6 and 5 in comparison to Comparative Example 4a and 4b,respectively. In these plots total EO (right axis, in grams) and EOsolution concentration (left axis, in wt %) (as determined by a vaporliquid equilibrium model) are plotted as a function of the reactiontime.

The plots start with the introduction of catalyst (t=0) and end with theisopropanol reaction quench. A total of 100 g of EO was added to eachrun.

FIG. 1 is a comparison of Example 6 and Comparative Example 4a.

FIG. 2 is a comparison of Example 5 and Comparative Example 4b.

It is evident from both figures that the EO is consumed much faster whena catalyst additive is present in addition to the Zn alkoxide catalyst(Examples 5 and 6 according to the present invention) than in thepresence of zinc alkoxide catalyst alone (Comparative Example 4a and4b). In Example 6 EO is consumed as fast as it is fed, never increasingabove about 4.5% solution concentration. After 117 min, virtually all ofthe added EO is consumed (final concentration is 0.2%), and the reactionis quenched. In Comparative Example 4a, EO must be added to the reactorat a slower rate and approaches 7% solution concentration. After 285min, the solution concentration is 2.4% and the reaction is quenched.Similarly for Example 5, a full 100 g of EO is consumed in 100 min(final EO concentration is 0.1%), much faster than in ComparativeExample 4b.

Example 7 Polymerization of EO with Zinc Alkoxide Catalyst andMagnesium-Bis-(2-Ethylhexanolate) Plus 2-Ethylhexanol

EO polymerization was carried out as described in Comparative Example4a. Similar to Example 5 the zinc alkoxide catalyst slurry of ReferenceExample 1 was pre-mixed with the additive before being added to the EOcharged reactor. Here, the additive was prepared in hexanes as inReference Example 2 except that an excess of 2-ethylhexanol was used (22mL (instead of 15 mL) of a 1.28 M hexanes solution (28 mmol) of2-ethylhexanol) resulting in the presence of unreacted 2-ethylhexanol.After the di-n-butylmagnesium and 2-ethylhexanol reagents reacted toform magnesium-bis-(2-ethylhexanolate) plus 2-ethylhexanol, 6 mL of 0.4M zinc alkoxide catalyst (2.4 mmol) were added to the solution. Theresulting slurry was sealed in a serum vial for transport to thereactor. Here the catalyst/additive solution was injected into a reactorprecharged with 40 g of EO. After 276 min, 1.5 mL of isopropyl alcoholwere charged into the reactor and the reactor was cooled. The polymerwas isolated and stabilized as described in Example 4a. The PEO yieldwas 59.8 g. A 1 wt. % aqueous solution of the polymer product wasdetermined to have a viscosity of 80 mPa·s (well below the 1 wt. %analysis scale), while a 2 wt % aqueous solution gave a viscosity of 383mPa·s (spindle no. 1, 10 rpm, 1 min measurement time), and a 5 wt. %aqueous solution gave a viscosity of 14,920 mPa·s (spindle no. 2, 2 rpm,5 min measurement time).

Example 8 Polymerization of EO with Zinc Alkoxide Catalyst and LithiumOctanolate Additive Plus Octanol

EO polymerization was carried out as described in Comparative Example4a. Similar to Example 6 the zinc alkoxide catalyst slurry of ReferenceExample 1 was pre-mixed with the additive before being added to the EOcharged reactor. Here, the additive was prepared in hexanes as inReference Example 3 except that an excess of octanol was used (11.1 mmolinstead of 9.8 mmol) resulting in the presence of unreacted octanol.After the n-butyllithium and octanol reagents reacted to formlithium-octanolate plus octanol, 8 mL of 0.4 M zinc alkoxide catalyst(3.2 mmol) were added to the solution. The resulting slurry was sealedin a serum vial for transport to the reactor. Here the catalyst/additivesolution was injected into a reactor precharged with 28 g of EO. After180 min, 1.5 mL of isopropyl alcohol were charged into the reactor andthe reactor was cooled. The polymer was isolated and stabilized asdescribed in Comparative Example 4a. The PEO yield was 90.3 g. A 1 wt. %aqueous solution of the polymer product was determined to have aviscosity of 240 mPa·s (spindle no. 2, 2 rpm, 5 min measurement time).

It is evident from the solution viscosities of the PEOs obtained thatthe catalyst additive of Examples 5 acts as molecular weight enhancerwhereas the catalyst additives of Examples 7 and 8 act as molecularweight reducing (limiting) agents. In addition, the catalyst additivesof Examples 5 and 6 contribute significant rate enhancement of the EOpolymerization reaction relative to Zn catalyst only experiments.

What is claimed is:
 1. A catalyst formulation comprising: (a) a Zncatalyst comprising a Zn compound having alcoholate ligand(s) derivedfrom one or more polyols, and (b) a catalyst additive comprising a metalcompound (i) having alcoholate ligand(s) derived from one or monohydricalcohol wherein the metal is selected from: (I) group 2 metals, (II) Li,and (III) combinations of at least two metals selected from (I) and(II).
 2. The catalyst formulation of claim 1 wherein the Zn compound ofthe Zn catalyst (a) is selected from: (a1) a Zn alcoholate of one ormore polyols, and (a2) a heteroleptic Zn alcoholate of one or morepolyols and one or more monohydric alcohols and/or water.
 3. Thecatalyst formulation of claim 2 wherein the Zn catalyst (a) comprises aZn alcoholate (a1) of one or more polyols and a Zn alcoholate (a3) ofone or more monohydric alcohols.
 4. The catalyst formulation of claim 1wherein the Zn catalyst (a) comprises a Zn compound having alcoholateligand(s) derived from one or more diols.
 5. The catalyst formulation ofclaim 2 wherein the Zn compound of the Zn catalyst (a) is a heterolepticZn alcoholate (a2) of one or more polyols and one or more monohydricalcohols selected from monohydric aliphatic alcohols includingmonohydric halosubstituted aliphatic alcohols.
 6. The catalystformulation of claim 5 wherein the Zn compound of the Zn catalyst (a) isa heteroleptic Zn alcoholate (a2) of 1,4-butanediol and ethanol.
 7. Thecatalyst formulation of claim 1 wherein the catalyst additive (b)comprises a metal compound (i) having alcoholate ligand(s) derived fromone or monohydric aliphatic, cycloaliphatic or mixedaliphatic/cycloaliphatic alcohols.
 8. The catalyst formulation of claim1 wherein the metal compound (i) of the catalyst additive (b) isselected from: (b1) a metal alcoholate of one or more monohydricalcohols, and (b2) a heteroleptic metal complex having alcoholateligand(s) derived from one or more monohydric alcohols andnon-alcoholate ligand(s).
 9. The catalyst formulation of claim 1 whereinthe catalyst additive additionally comprises (ii) a monohydric alcohol.10. A process for polymerizing an epoxide monomer comprising carryingout the process in the presence of a catalyst formulation comprising:(a) a Zn catalyst comprising a Zn compound having alcoholate ligand(s)derived from one or more polyols, and (b) a catalyst additive comprisinga metal compound (i) having alcoholate ligand(s) derived from one ormonohydric alcohol wherein the metal is selected from: (I) group 2metals, (II) Li, and (III) combinations of at least two metals selectedfrom (I) and (II).
 11. The process of claim 10 wherein a poly(olefinoxide) having a weight average molecular weight of at least 30,000 isprepared.
 12. The process of claim 10 wherein a poly(ethylene oxide) isprepared.
 13. The process of claim 11 wherein a poly(ethylene oxide) isprepared.